In many downhole environments, packers or similar sealing devices are used to seal sections of the well bore so that, for example, hydrocarbons can be extracted from a well bore section into the production tube without leakage up or down the annulus between the well bore surface and the production tube.
Elastomeric seal elements are widely used in conventional packers as they are relatively easy to manipulate and have good sealing properties once engaged with a well bore surface. A conventional packer is also often provided with one or more seal back-ups to prevent extrusion of the elastomeric sealing element in the annulus when the sealing apparatus is under pressure.
However, the mechanical properties of elastomers can deteriorate as pressure and/or temperature increases. The performance of these conventional packers are also affected when, in addition to the high pressure and/or high temperature environment, the seal has to seal across a large annulus. These high expansion seals are particularly vulnerable in the aggressive environments described.
There is a desire within the oil industry to operate in high temperature and high pressure environments, and there is need for a sealing apparatus which can operate successfully in these environments, particularly a high expansion sealing apparatus.